There is an organic electroluminescence (EL) element as one of light sources for an illumination device or a display. The organic EL element is vulnerable to moisture, and thus is required to be sealed. In a sealing structure of the organic EL element, a sealing film may be used, for example, as disclosed in Patent Document 1. In Patent Document 1, alumina formed by an atomic layer deposition method is used as the sealing film.